Apparatus for detecting front edge of a document and determining the home position of an image scanning module

ABSTRACT

An apparatus for detecting front edge of a document and determining home position of an image scanning module has a detecting light source near an outlet end of a document feeding track and aligned with an image reader of the image scanning module. The detecting light source emits a detecting light to be received by the image reader. By detecting whether the detecting light is received by the image reader, the front edge of the document can be detected to activate the image scanning module. And it can also determine whether or not the image scanning module has arrived on a home position.

PRIORITY STATEMENT

This Non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No(s). 94123801 filed in Taiwan on Jul. 13, 2005,the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to an image scanning device, and particularly toan apparatus for detecting front edge of a document and determining thehome position of an image scanning module

2. Related Art

Referring to FIGS. 1, 2A and 2B, a conventional image scanning device 1such as a Multi-Function Peripheral (MFP), image scanner, or copier isequipped with an image scanning function to duplicate and transformimages into electronic data for storage or into documents by printing.The image scanning device 1 has a scanning platform 2, an image scanningmodule 3 below the scanning platform 2, and a conveyor 4 to drive theimage scanning module 3 back and forth. While scanning images on adocument, one side of the document to be scanned is placed on thescanning platform 2. The conveyor 4 drives the image scanning module 3back and forth to scan the images on the document.

For scanning a greater amount of documents, an Automatic Document Feeder(ADF) 5 is used to feed the documents sequentially into the imagescanning device 1. The documents 6 to be scanned are moved above theimage scanning module 3 to perform scanning. The documents 6 are fed bythe ADF 5, and the image scanning module 3 remains stationary.

The image scanning module 3 is at a standby state in normal conditions.When the front edge 6 a of a document arrives at the upper side of theimage scanning module 3, the image scanning module 3 is activated toprocess scanning. Such a design aims to save power and increase the lifespan of the image scanning module 3. It also prevents the image scanningmodule 3 from scanning the area outside the document 6. So that thememory buffer space occupied by the electronic data transformed from theimage of the document 6 will be minimized. In the conventional approachthe document 6 is driven by a plurality of feeding rollers 5 a. Atrigger 5 b of a detector is used to be pushed by the front edge 6 a ofthe document 6. The feeding rollers 5 a rotate and feed the document 6through a document feeding track 7 towards the image scanning module 3.Before the document 6 arrives at the image scanning module 3, the frontedge 6 a of the document 6 pushes the trigger 5 b to generate a triggersignal. Depending on the distance between the trigger 5 b and the imagescanning module 3 and the displacement of the document 6 generated byrotation of the feeding rollers 5 a, a control circuit in the scanningdevice 1 starts counting the revolutions of the feeding rollers 5 a.When the document displacement generated by the rotation of the feedingrollers 5 a is approximate to the distance between the trigger 5 b andthe image scanning module 3, the image scanning module 3 is activated toprocess scanning. However, the trigger 5 b is a mechanical structure,its precision is lower. When the trigger 5 b is pushed by the document 6to generate the trigger signal, an error occurs on the actual positionof the front edge 6 a of the document 6. In addition, an error indocument displacement is occurred while the feeding rollers 5 a drivethe document 6. The error in actual position of the front edge 6 a andthe error in document displacement result in the image scanning module 3not being activated as the front edge 6 a just arrives, so thatdistortion of image scanning is occurred.

If the ADF 5 is not used, and manual feeding of a single document isemployed, one document is placed on the scanning platform 2 with thetext or image side down. One edge of the document 6 has to be aligned ona starting line (not shown in the drawings). The starting linecorresponds to the home position of the image scanning module 3. Duringscanning operation, the conveyor 4 drives the image scanning module 3 toperform scanning operation from the home position until reaching anotheredge of the document. After the scanning operation is finished, theconveyor 4 moves the image scanning module 3 back to the home position.Then the conveyor 4 stops driving the image scanning module 3. The imagescanning module 3 stops on the home position to wait for the nextscanning operation. To control the image scanning module 3 to stopprecisely on the home position, the general approach is to install afirst sensor 8 a and a second sensor 8 b on the image scanning module 3and the image scanning device 1 respectively. The first sensor 8 acorresponds to the home position. When the image scanning module 3 islocated on the home position, induction occurs between the first sensor8 a and the second sensor 8 b and a detection signal is generated tostop operation of the conveyor 4. This approach requires additionalsensors on the image scanning module 3 and the image scanning device 1.Thus fabrication time and cost are higher.

SUMMARY OF THE INVENTION

In view of the aforesaid problems, the object of the invention is toprovide an apparatus for detecting the front edge of a document anddetermining the home position of an image scanning module that canoperate precisely and simplify the structure of a scanning device.

In order to achieve the foregoing object, the apparatus for detectingthe front edge of a document and determining the home position of animage scanning module according to the invention is installed on animage scanning device to detect the front edge of the document ordetermine the home position of the image scanning module. The apparatusof the invention includes an image scanning module, a document feedingtrack and a detecting light source. The image scanning module includesan image reader and a scanning light source. The document feeding trackhas an inlet end and an outlet end. The inlet end is to feed documentssequentially into the document feeding track, and the outlet end is toreceive the documents discharged from a paper path of the documentfeeding track corresponding to the image scanning module. The detectinglight source is located on the documents feeding track and over whichthe document passes to emit detecting light received by the image readerof the image scanning module. Thereby, when the front edge of a documentarrives between the image reader and the detecting light source, thedetecting light is blocked by the document and then the image scanningmodule is activated. The scanning light source starts emitting scanninglight to perform scanning operation.

As the image scanning module is moved back to a home position afterscanning a document placed on the scanning platform, the detecting lightsource emits the detecting light simultaneously corresponding to thehome position of the image scanning module. When the image scanningmodule is located on the home position, the image reader can receive thedetecting light and generate a stopping signal to enable the imagescanning module to stop on the home position precisely.

The invention can achieve the following results: by merely adding adetecting light source to cooperate with image scanning module,detection of the document front edge and determination of the homeposition of the image scanning module can be accomplished at the sametime. Besides, the structure of the apparatus is simplified, so thatfabrication is simpler. When adopted for detecting the front edge of adocument, the present invention can precisely detect the front edge ofthe document above the image scanning module. The precision is higherthan the conventional mechanical detection design. The present inventionalso can position the image scanning module on the home position at thesame time without adding extra detection elements.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a conventional automatic document feederand scanning device;

FIGS. 2A and 2B are fragmentary enlarged views of a conventionalautomatic document feeder;

FIG. 3 is a sectional view of an embodiment of the invention;

FIG. 4 is a fragmentary exploded view of an embodiment of the invention;

FIGS. 5A and 5B are schematic views of an embodiment of the inventionfor detecting a document front edge; and

FIGS. 6A and 6B are schematic views of an embodiment of the inventionfor positioning an image scanning module on a home position.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus for detecting the front edge of a document and determiningthe home position of an image scanning module of the invention isinstalled on an image scanning device that has an automatic documentfeeder to detect the front edge of the document and positioning theimage scanning module precisely on a home position. The image scanningdevice may be a Multi-Function Peripheral (MFP), flatbed scanner,copier, or the like for scanning a large amount of documents.

Referring to FIG. 3, the scanning device generally includes a body 100to perform scanning operation and an automatic document feeder 200.

The body 100 includes a housing 110 with a scanning platform 111 to holda document 300 to be scanned. Under the scanning platform 111, there area conveying module 120 and an image scanning module 130. The conveyingmodule 120 is for conveying the image scanning module 130 from a homeposition back and forth under the scanning platform 111, so that theimage scanning module 130 can scan the document 300 which is placed onthe scanning platform 111. The conveying module 120 includes a motor 121and a conveying element 122. The motor 121 may be a step motor or a DCmotor. The conveying element 122 may be a screw, a belt, a combinationof gears and racks, or a combination thereof to be coupled with themotor 121 and the image scanning module 130, so that the image scanningmodule 130 can be driven by the motor 121 to move back and forth. Also,the body 100 has a control circuit (not shown in the drawings) tocontrol the image scanning module 130 and the motor 121.

The image scanning module 130 includes at least an image reader 131 anda scanning light source 132. The image reader 131 has a photosensitiveelement (such as CCD, CIS or the like), lenses and reflective mirrors toreceive a light and transform the light to electronic signals. Thescanning light source 132, such as a tubular fluorescent lamp,irradiates a light to the document 300, and then a reflex reflected fromthe document 300 is received by the image reader 131. Details andoperation principles of the image reader 131 and the scanning lightsource 132 are known in the art and are thus omitted hereinafter.

The automatic document feeder 200 is located on one side of the top ofthe body 100. It has a feeding tray 210, a document feeding track 220, aplurality of feeding rollers 230 and an exit tray 240. The feeding tray210 is to hold a plurality of documents 300 to be scanned. The documents300 are fed sequentially into the document feeding track 220. Thedocument feeding track 220 has an inlet end 221 and an outlet end 222.The inlet end 221 is connected to the feeding tray 210 to receive thedocuments 300 sequentially into the document feeding track 220. Theoutlet end 222 is adjacent one side of the scanning platform 111 andalso is connected to the exit tray 240 for receiving the documents 300discharged from a paper path P (as the dotted line) of the documentfeeding track 220, so that a scanning window 223 is formed over thescanning platform 111 corresponding to the home position of the imagescanning module 130 and opposite the image scanning module 130. Theimage scanning module 130 can scan the document 300 passing over thescanning window 223 from the home position through the scanning window223. The feeding rollers 230 are located on two sides of the documentfeeding track 220 and rotate on two sides thereof to drive the document300 from the inlet end 221 towards the outlet end 222.

The document feeding track 220 has a detecting window 224 over which thedocument 300 passes corresponding to the scanning window 223. Adetecting light source 250 is mounted in the detecting window 224 nearthe outlet end 222 and aligned with the image reader 131. When the imagescanning module 130 is located on the home position, it is correspondingto the detecting light source 250. The detecting light source 250 canemit a detecting light S to be received by the image reader 131 of theimage scanning module 130, so that the image scanning module 130maintains a selected voltage potential.

Referring to FIGS. 4, 5A and 5B, when the automatic document feeder 200conveys the document 300, the image scanning module 130 is located onthe home position to scan the document 300 through the scanning window223. The document 300 are stacked on the feeding tray 210 and loadedsequentially into the document feeding track 220 by the feeding rollers230 from the inlet end 221 towards the outlet end 222. Then the imagescanning module 130 scans each of the documents 300 passing over thescanning window 223. Before the document 300 arrives in the scanningwindow 223, the image scanning module 130 is on standby mode so that thescanning light source 132 does not emit scanning light to waste powerand reduce the life span of the scanning light source 132. The imagereader 131 also does not have to read a great amount of blank dataoccupying unnecessary memory buffer space of the scanning device.

When the front edge of the document 300 arrives in the scanning window223 and between the image reader 131 and detecting light source 250, thedetecting light S is blocked by the document 300, so that the imagereader 131 cannot receive the detecting light S. Then the image scanningmodule 130 changes its voltage potential. Hence the control circuittransmits a trigger signal to activate the image scanning module 130,and the scanning light source 132 starts to irradiate scanning light tothe document 300 through the scanning window 223. The image reader 131receives a reflex reflected from the document 300 and transforms theimage of the document 300 into electronic data. After the document 300has passed over the scanning window 223 completely and leaves the outletend 222 of the document feeding track 220, the image scanning module 130suspends scanning operation. The scanning light source 132 is turnedoff, and the image scanning module 130 enters the standby mode.Meanwhile, the detecting light S emitted from the detecting light source250 is continuously received by the image reader 131 of the imagescanning module 130 and waits the detecting light S to be blocked toactivate the scanning operation again. Only when the front edge of thedocument 300 arrives above the image reader 131 to block the detectinglight S, the image scanning module 130 can be activated, so theprecision of detecting the front edge of the document is enhanced.

When the automatic document feeder 200 is not in use, the document 300can be placed on the scanning platform 111 individually, and the imagescanning module 130 is driven by the conveying module 120 from the homeposition to move back and forth horizontally to scan the document 300.The image scanning module 130 has to perform the scanning operation fromthe home position, otherwise the area scanned of the document will besmaller than the actual size of the document 300 and a portion of imagedata could be lost. Or the area scanned of the document will be greaterthan the actual size of the document 300 and result in scanning a largeamount of blank data occupying unnecessary memory buffer space. Theembodiment of the invention can also determine the home position of theimage scanning module 130 precisely.

Referring to FIGS. 6A and 6B, if the image scanning module 130 is notlocated on the home position, the image reader 131 cannot receive thedetecting light S emitted from the detecting light source 250 in theevent. As a result, the image scanning module 130 maintains at anothervoltage potential. After the image scanning module 130 has finished aprior scanning operation, the scanning light source 132 is turned off,and the conveying module 120 starts driving the image scanning module130 moving from another side of the scanning platform 111 towards thehome position. When the image scanning module 130 arrives at the homeposition, the image reader 131 receives the detecting light S emittedfrom the detecting light source 250. Thus, the voltage potential of theimage scanning module 130 is altered to the selected one and a stoppingsignal is generated. The control circuit of the scanning device stopsthe conveying module 120 to drive the image scanning module 130, theimage scanning module 130 stays on the home position, and determinationof home position of the image scanning module 130 is completed.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. An apparatus for detecting front edge of a document that is installedon a scanning device to detect the front edge of the document,comprising: an image scanning module which includes an image reader anda scanning light source; a document feeding track which has an inlet endfor feeding documents sequentially into the document feeding track andan outlet end for receiving the documents discharged from a paper pathof the document feeding track corresponding to the image scanningmodule; and a detecting light source located on the document feedingtrack and over which the document passes corresponding to the imagereader to emit a detecting light which is received by the image reader;wherein when the front edge of the document arrives between the imagereader and the detecting light source to block the detecting light, theimage scanning module is activated and the scanning light source startsemitting a scanning light to perform a scanning operation.
 2. Theapparatus of claim 1, wherein the scanning device includes a housingwhich has a scanning platform on an upper side, the image scanningmodule being located under the scanning platform.
 3. The apparatus ofclaim 2, wherein the document feeding track has a scanning windowcorresponding to one side of the scanning platform and opposite to theimage scanning module.
 4. The apparatus of claim 2 further comprising aconveying module located under the scanning platform to drive the imagescanning module to move back and forth under the scanning platform. 5.The apparatus of claim 4, wherein the conveying module includes a motorand a conveying element, the conveying element is coupled with the motorand the image scanning module.
 6. The apparatus of claim 5 furthercomprising a control circuit to control the image scanning module andthe motor.
 7. The apparatus of claim 1 further comprising a plurality offeeding rollers which are located on two sides of the document feedingtrack and rotate to drive the document from the inlet end of thedocument feeding track towards the outlet end.
 8. The apparatus of claim1, wherein the document feeding track has a detecting window over whichthe document passes corresponding to the image reader, the detectinglight source being located in the detecting window.
 9. A scanning deviceequipped with an apparatus for determining the home position of an imagescanning module, comprising: a housing having a scanning platform on anupper surface; an image scanning module which is located under thescanning platform, having an image reader and a scanning light source; aconveying module to drive the image scanning module to move back andforth from a home position under the scanning platform; and a detectinglight source which is located above the scanning platform correspondingto the home position of the image scanning module, to emit a detectinglight to be received by the image reader.
 10. The scanning device ofclaim 9, wherein the conveying module includes a motor and a conveyingelement, the conveying element is coupled with the motor and the imagescanning module.
 11. The scanning device of claim 10 further comprisinga control circuit to control operations of the image scanning module andthe motor.
 12. An automatic document feeding mechanism, comprising: adocument feeding track which has an inlet end and an outlet end, toreceive a document from the inlet end moving towards the outlet; and adetecting light source located on the document feeding track and overwhich the document passes to emit a detecting light.
 13. The automaticdocument feeding mechanism of claim 12 further comprising a plurality offeeding rollers located on two sides of the document feeding trackrotating to drive a document from the inlet end of the document feedingtrack moving towards the outlet end.
 14. The automatic document feedingmechanism of claim 12, wherein the document feeding track has adetecting window over which the document passes, the detecting lightsource being located in the detecting window.
 15. The automatic documentfeeding mechanism of the claim 12, wherein the detecting light source islocated near the outlet end of the document feeding track.